Dynamic behaviour of wind power systems equipped with automatically regulated Continuously Variable Transmission

High efficiency levels may be attained by wind turbines operating at varying speeds when the machine is made to run at a constant tip speed ratio. Previous papers have suggested incorporating a continuously variable transmission (c.v.t.) to achieve this purpose. Following the general recommendation of using efficient, reliable and economical technologies in wind power systems, one of these papers investigated whether a V-belt c.v.t. with automatically adjustable speed was compatible with a wind power system. The investigations in this case were carried out under steady-state conditions. In this paper, the behaviour of a wind power system equipped with a c.v.t. will be examined in turbulent wind conditions using a dynamic model. The simulation results will show that, when the actual wind speed fluctuations are taken into account, incorporating a c.v.t. between the turbine and the electric generator yields greater advantages in terms of energy output than it does when the system is assessed in the steady-state. The better quality of the electrical energy supplied will be examined and compared to that produced by a constant speed system. Finally, the behaviour of a wind power system equipped with a c.v.t. will be assessed as the temporal characteristics of the wind gusts change